ADD: linear storage model to be used with all formulations based on a…

… predefined problem specification.

CHANGELOG.md

@@ -3,6 +3,8 @@
 ## staged
 
 - Updated to use the new `NonlinearExpr` syntax introduced in JuMP v1.15. In most cases, there should be no user-visible changes. `Breaking change`: PowerModels v0.21.2+, PowerModelsDistribution v0.16+, and JuMP v1.23.2+ should be used to support new compatibility (enforced in `Project.toml`). This upgrade signifcantly decreases the time to build large-scale models.
+- Added a new problem formulation `opfitd_storage_linear.jl` that removes the complementary_nl constraint by making rs=0 and xs=0, allows the use of a linear storage model for T&D co-optimization using nonlinear formulations.
+- Fixed issue with functions in `objective_storage.jl` not transforming correctly the cost.
 
 ## v0.9.2
 

src/PowerModelsITD.jl

@@ -48,6 +48,7 @@ module PowerModelsITD
     include("core/objective_dmld_simple.jl")
     include("core/objective_storage.jl")
     include("core/solution.jl")
+    include("core/constraint_storage_linear.jl")
 
     include("data_model/transformations.jl")
 
@@ -67,6 +68,7 @@ module PowerModelsITD
     include("prob/opfitd_oltc.jl")
     include("prob/opfitd_dmld.jl")
     include("prob/opfitd_storage.jl")
+    include("prob/opfitd_storage_linear.jl")
 
     # This must come last to support automated export.
     include("core/export.jl")

src/core/constraint_storage_linear.jl

@@ -0,0 +1,38 @@
+"""
+    constraint_storage_losses_linear(pm::_PM.AbstractPowerModel, i::Int; nw::Int=_PM.nw_id_default)
+
+Template function for storage loss constraints for linear model - transmission.
+"""
+function constraint_storage_losses_linear(pm::_PM.AbstractPowerModel, i::Int; nw::Int=_PM.nw_id_default)
+    storage = _PM.ref(pm, nw, :storage, i)
+
+    # force storage model to be linear
+    storage["r"] = 0.0
+    storage["x"] = 0.0
+
+    _PM.constraint_storage_losses(pm, nw, i, storage["storage_bus"], storage["r"], storage["x"], storage["p_loss"], storage["q_loss"])
+end
+
+
+"""
+    constraint_mc_storage_losses_linear(pm::_PMD.AbstractUnbalancedPowerModel, i::Int; nw::Int=_PMD.nw_id_default)::Nothing
+
+Template function for storage loss constraints for linear model - distribution.
+"""
+function constraint_mc_storage_losses_linear(pmd::_PMD.AbstractUnbalancedPowerModel, i::Int; nw::Int=_PMD.nw_id_default)::Nothing
+    storage = _PMD.ref(pmd, nw, :storage, i)
+
+    # force storage model to be linear in nonlinear formulations
+    storage["r"] = 0.0
+    storage["x"] = 0.0
+
+    _PMD.constraint_mc_storage_losses(pmd, nw, i, storage["storage_bus"], storage["connections"], storage["r"], storage["x"], storage["p_loss"], storage["q_loss"])
+    nothing
+end
+
+
+""
+function constraint_mc_storage_losses_linear(pmd::_PMD.AbstractUBFModels, i::Int; nw::Int=_PMD.nw_id_default)::Nothing
+    _PMD.constraint_mc_storage_losses(pmd, i; nw=nw)
+    nothing
+end

src/core/objective_storage.jl

@@ -125,7 +125,7 @@ function _objective_itd_min_fuel_cost_polynomial_linquad_storage(pmitd::Abstract
     for (n, nw_ref) in _PMD.nws(pmd)
         for (i, strg) in nw_ref[:storage]
             dsch = _PMD.var(pmd, n, :sd, i)                                                     # get discharge power value
-            strg_cost_dollar_per_pu = strg["cost"][1]#*nw_ref[:settings]["sbase_default"]        # convert from $/kWh -> $/pu
+            strg_cost_dollar_per_pu = strg["cost"][1]*nw_ref[:settings]["sbase_default"]        # convert from $/kWh -> $/pu
             strg_cost_dollar_per_pu = round(strg_cost_dollar_per_pu, digits=4)
             pmd_strg_cost[(n,i)] = strg_cost_dollar_per_pu*dsch                                 # compute discharge cost
         end
@@ -260,7 +260,7 @@ function _objective_itd_min_fuel_cost_polynomial_nl_storage(pmitd::AbstractPower
     for (n, nw_ref) in _PMD.nws(pmd)
         for (i, strg) in nw_ref[:storage]
             dsch = _PMD.var(pmd, n, :sd, i)                                                     # get discharge power value
-            strg_cost_dollar_per_pu = strg["cost"][1]#*nw_ref[:settings]["sbase_default"]        # convert from $/kWh -> $/pu
+            strg_cost_dollar_per_pu = strg["cost"][1]*nw_ref[:settings]["sbase_default"]        # convert from $/kWh -> $/pu
             strg_cost_dollar_per_pu = round(strg_cost_dollar_per_pu, digits=4)
             pmd_strg_cost[(n,i)] = strg_cost_dollar_per_pu*dsch                                 # compute discharge cost
         end